“It's important for us to understand the gaps and loopholes in our immigration system,” the Iowa senator said Friday during an immigration reform hearing. “While we don't yet know the immigration status of people who have terrorized the communities in Massachusetts, when we find out it will help shed light on the weaknesses of our system. How can individuals evade authority and plan such attacks on our soil?”

Tamerlan Tsarnaev, 26, and his brother Dzhokhar, 19, are suspected of planting bombs at the Boston Marathon, killing three and wounding 170. Police killed Tamerlan in an shootout early Friday, and Dzhokhar was captured by police Friday night. The brothers were ethnic Chechens who were born in Kyrgyzstan, and by 2001, the family had moved to Dagestan, which borders Chechnya before being granted asylum in the United States. The younger brother became a U.S. citizen last year.

Grassley said the brothers' immigrant status should be cause for alarm, ABC News reports.
"How can we beef up security checks on people who wish to enter the United States?"

Grassley said. "How do we ensure that people who wish to do us harm are not eligible for benefits under the immigration laws, including this new bill before us?"

While federal authorities were pursuing the Tsarnaev brothers Friday, the Senate Judiciary Committee was holding its first full hearing on immigration reform. Earlier this week, the bipartisan “Gang of Eight” senators unveiled a proposal that included added border-security rules and new citizenship eligibility for immigrants who came in illegally.

Others at the hearing said the new measures will allow for stronger tracking and security.
Senate Majority Whip Dick Durbin said the proposals, which offer a path to citizenship, tighten border security, require worker identifications and track visas will make the nation safer.

“First, we’re going to make a dramatic investment in our border with Mexico,” the Iowa Democrat said in an interview with Bloomberg Television’s “Political Capital with Al Hunt.” “We’re going to close the gaps in that border once and for all.”

Meanwhile, New York Democratic Sen. Chuck Schumer, a Gang of Eight member said he'd “ like to ask that all of us not jump to conclusions regarding the events in Boston or try to conflate those events with this legislation.

“In general, we're a safer country when law enforcement knows who is here, has their fingerprints, photos, etc., (and) has conducted background checks and no longer needs to look at needles through haystacks,” he said.

Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina, also part of the Gang of Eight, said the attacks are a reason to move ahead with immigration reform.

"In the wake of this week's terrorist attack in Boston, some have already suggested that the circumstances of this terrible tragedy are justification for delaying or stopping entirely the effort for comprehensive immigration reform. In fact the opposite is true," McCain and Graham said in a written statement.